1/1×3+1/3×5+1/5×7+…1/17×19+1/19×21这道题如何简便运算?用算术法做!答对加50分!

1/1*3+1/3*5+1/5*7……+1/17*19 简算:1/(1*3)+1/(3*5)+1/(5*7)+……+1/(99*101)= 1/1*3+1/3*5+1/5*7……1/97*99= 1×3/1+3×5/1+5×7/1……+49×51/1 1/1×3 1/3×5 1/5×7 …… 1/2009×2010等于多少 1/1*3+1/3*5+1/5*7+……+1/2003*2005结果是什么? 1/1×3+1/3×5+1/5×7+……+1/47×49简便计算 1/1*3+1/3*5+1/5*7+……+1/47*49 1/3×1/5+1/5×1/7+1/7×1/9+……+1/97×1/99 1+1/1*3+1/3*5+1/5*7+1/7*9+……+1/99*101=? 1×1/3+1/3×1/5+1/5×1/7+……+1/99×1/101 1/3*5+1/5*7+1/7*9+……1/97*99 计算1/1×3+1/3×5+1/5×7+…+1/1997×1999 计算：1/1*3+1/3*5+1/5*7+…+1/99*101.怎么来? 1/(1+3)+1/(3+5)+1/(5+7)…+1/(99+101)=( )简便计算 1/1*3+1/3*5+1/5*7+…+1/97*99找规律计算 1/1×3+1/3×5+1/5×7+…+1/99×101 等于多少啊 1/3×1+1/3×5+1/5×7…1/2009×2011等于多少